The ornamental design for a hairroller, as shown and described.
FIG. 1 is a right side view of a hair roller showing my new design, the left side view being a mirror image thereof;
FIG. 2 is a top view thereof, the bottom view being a mirror image thereof;
FIG. 3 is a front view thereof, the back view being a mirror image thereof; and,
FIG. 4 is a top perspective view thereof.
The broken lines shown in the figures are used to illustrate stitching that forms no part of the claimed design.
The article is shown with a symbolic break in length. The appearance of any portion of the article between the break lines forms no part of the claimed design.